Raw printing evokes failed side-band request

[Kaleb Pederson]

I've enable raw printing by allowing application/octet-stream in mime.types and mime.convs, which worked for quite a while.  Although I'm not positive, I believe that a recent cups upgrade caused some problems with "raw" printing, even though regular printing works fine.

I'm trying to print a raw file as follows:

$ lpr -P LaserPrinter -o raw myfile.raw

And I see (dates/times truncated for readability):

$ tail -f /var/log/cups/error_log
Adding start banner page "none" to job 377.
Adding end banner page "none" to job 377.
Job 377 queued on "LaserPrinter" by "kibab".
Started backend /usr/libexec/cups/backend/usb (PID 6255) for job 377.
[Job 377] Failed to read side-channel request!

(with last line above repeated about 8 times)

Any suggestions on how I can isolate the problem?

Thanks.

--Kaleb